The present invention relates to an apparatus for checking and measuring the momentary value of a variable physical magnitude such as the volume of a liquid in a container or tank, a temperature, viscosity, or a velocity, for example. The present invention also relates to a method providing a real time indication of the momentary value of the variable physical magnitude, and also to an enclosure or tank containing a liquid and provided with such device.
For the purpose of monitoring, or for safety or maintenance reasons, among others, there is often present a requirement, as is well known, for obtaining a quantitative indication, either by a simple level indicator or better yet by a more precise volumetric indicator of the absolute value of certain physical parameters tied to a variable factor such as elapsed time, or the available volume of a liquid in a reservoir of small capacity, such as the lubricating oil contained in the crankcase of an internal combustion engine or in the transmission housing of a motor vehicle or, on the contrary, of the liquid contained in a large capacity tank, reservoir or cistern, containing several thousand liters of liquid.
Devices for that purpose, made according to modern day technology, and which permit to give an indication of the level or to measure the variations in such quantities, provide a relatively weak signal at their output which is of little use without amplification requiring auxiliary energy sources.
The result is that such devices have poor sensitivity and accuracy unless they call upon auxiliary energy sources, and when they are provided with an amplification device, they become rather complex and are therefore somewhat costly to manufacture.
The principal object of the present invention is to remedy the inconveniences of the prior art and to provide a method and apparatus for supplying an indication of the momentary instantaneous value of a variable physical magnitude, by simple means and thus at a relatively low cost, and which is nevertheless sturdy and reliable such as to cut down on maintenance costs. In addition, a device according to the invention does not depend on the existence of auxiliary energy sources, while still permitting checking or monitoring at a remote location.
It will be appreciated that an apparatus according to the present invention comprises elements which are completely free to move, that is which are entirely independent of mechanical, magnetic or electrical connections, for example. The result is that such a freedom of motion provides the device of the invention with considerable sensitivity and accuracy which, as is evident, are basic qualities for any type of measuring instruments.
The object of the present invention therefore is to provide a device capable of giving an indication of the momentary value of a variable physical magnitude characterized in that it comprises a movable transducer in engagement with the physical characteristics to be measured and able to be freely displaced according to the smallest variation of said magnitude in opposite or alignment with a sensor in a rest or reference position, the transducer having a portion of varying cross-section displaceable opposite the sensor. Means are provided for displacing the sensor relative to the transducer to engage the sensor with the transducer as well as means for indicating the position of the sensor when in engagement with the transducer and for returning the sensor to its reference position.
According to a preferred embodiment, the device further comprises means for measuring the amount of displacement of the sensor between its reference position and its position in engagement with the transducer, said means being coupled directly or indirectly to the sensor, means for engaging the sensor with the transducer, such means for engaging the sensor with the transducer consisting of a spring and the sensor having a portion having a progressively varying cross-section on its full length capable of engaging the transducer at the portion of the transducer having itself a varying cross-section, the line of sight of the variation of the cross-section of the transducer and of the sensor being in a plane perpendicular to the axis of displacement of the sensor, the transducer and the sensor having one a female member and the other a male member of varying cross-sections complementary of each other, the engagement of the sensor against the transducer being effected through such members, male and female, the male member of the transducer-sensor arrangement being a cone having an axis parallel to the direction of displacement of said members, and the female member being a window formed in alignment with the male member, the width of the window varying from an end to the other and the edges of the window engageable with the male member being provided with a bevel or chamfer.
In a particularly advantageous structure, in which the female member is integral with the transducer and the male member is integral with the sensor, the female member is a window formed in a plate disposed between the two spaced-apart parallel walls of a housing and displaceable in unison with the transducer under the influence of the variations of the magnitude to be checked or monitored, and the sensor is urged toward the transducer in a direction substantially perpendicular to said walls which act, for the transducer-sensor assembly, as abutments when the two co-operating parts of the structure respectively engage and disengage.
A further object of the present invention is to provide a method for giving an indication of the momentary or instantaneous magnitude of a variable physical quantity characterized in associating the motion of a movable transducer with the variations of the magnitude to be measured, the transducer not touching any other element and being entirely free to be displaced when subjected to the minutest variation of said magnitude, in urging a sensor toward said transducer until a male member of one engages into a female member of the other, the female and male members having varying sections which are respectively complementary of each other, and in providing an indication of the position of said sensor when in engagement with the transducer.
Finally, the present invention has for object to provide a container or tank such as the crankcase of a motor vehicle, or any other reservoir or tank, provided with the device of the invention.
The many objects and advantages of the present invention will become readily apparent when the following description of the best modes contemplated for practicing the invention is read in conjunction with the accompanying drawing, giving examples of structures for illustrative purpose only and not for the purpose of limitation, and in which: